We begin by displaying some of the atomic rates
which are notable due to their departure from previous work, or to
their effects on the model results.
Figure 1 shows the ground state photoionization cross sections we adopt.
Each panel contains the cross sections for a given element, with various
curves for the respective ions. In most cases the various subshells of
a given ion are also plotted as separate non-overlapping curves. Resonance
structure near threshold of outer shells is apparent, particularly in ions
with Z10. The photoionization cross sections from many excited levels
also show resonance structure. This is illustrated in Figure 2,
which shows a few of the excited level cross sections for O VII. Notable are the
resonance features near 650 eV, corresponding to the 1-2 transitions in the
O VIII ion. Although cross sections with comparable resolution are available
for many ions from the opacity project, we adopt Gaussian average fits
to these for the great majority of excited levels. For O VII we include all
available cross sections at high resolution for ground and excited levels
with principle quantum number 4 in order to illustrate the
potential importance of the resonance structures in observed spectra.

Ground state collisional ionization rate coefficients are shown in
Figure 3. Each panel contains the rates for a given element as a function of
temperature.

Figure 4 shows the radiative recombination rates we adopt.
We emphasize that these are calculated by performing
a Milne integral (equation 3) over the photoionization cross section
for each of the bound levels of the recombined ion, and then summing over
those rates. This is in contrast to the more typical nebular
treatment in which such a sum is fit to an analytic formula as was
done by, e.g. [Aldrovandi and Pequignot 1973], and has the advantage that it
causes all rates to go to detailed balance ratios in the proper limit.
Each panel in Figure 4 contains the rates for a given
element. Also shown, as the dashed curves, are the rates
adopted in XSTAR v.1, i.e. those of [Gould and Thakur 1970] (hydrogenic ions)
[Arnaud and Raymond 1992] (for iron), and [Aldrovandi and Pequignot 1973] (all others).
Differences are prominent for elements such as C, O, and Fe, and
primarily reflect differences between the previous dielectronic recombination
rates and those adopted here (e.g. [Nahar 2000] and references therein).